The present invention relates generally to an apparatus and method for measuring the speed and/or acceleration of a vehicle. More particularly, the invention relates to the use of a projected radiation beam that is blocked by passing vehicles.
Various arrangements for measuring the speed and/or acceleration of a vehicle moving along a surface such as a roadway have been known. One such device uses radiation sources on one side of the roadway, projecting a beam across the roadway to be received by a respective detector. The detectors are on the opposite side of the roadway from the radiation sources. The detectors detect when the beam is blocked by a tire of the vehicle. A calculating circuit determines the speed and/or acceleration of the vehicle based on information from the detectors.
A disadvantage of this known arrangement is that the radiation sources and detectors must be placed on opposite sides of the roadway from each other. Since both the detectors and radiation sources require power to operate, this means that a separate power supply must be provided on each side of the roadway.
Another disadvantage of the known arrangement is that it is difficult to align the sources and detectors so that the beam hits the detector.
Still another disadvantage of the known arrangement is that there is no means for approximating the size and/or mass of the passing vehicle, information useful in the calculation of the Specific Power generated by the vehicle. Specific Power is crucial to correlating on-road in-use emissions from vehicles to stationary loaded-mode tests when the embodiment of this invention is applied to on-road in-use emissions testing.
No currently known embodiment of speed and acceleration can be implemented such that more than one group of sensors can connected in series (xe2x80x9cdaisy-chainedxe2x80x9d) to produce multiple sets of speed and acceleration measurements.
Yet another disadvantage of known arrangements is that there is no provision for a convenient support structure that can support more than one unit such as sender units, detector units, or reflector units, to provide a fixed spacing between the units while also permitting the support to be adjustable for uneven surfaces or for mounting on a curb when desired. Also, there is no provision for making such a support able to be disassembled for storage and/or transport.
Another disadvantage of the known arrangements is that each beam path across the road requires its own sender (or emitting) unit. Thus, for two beams crossing the road, two emitting units are needed.
The present invention provides a system and method that can form more than one beam crossing a vehicle path using one radiation emitter.
In one aspect, the invention provides an embodiment having an apparatus for measuring at least one of a speed and acceleration of a vehicle travelling on a vehicle path, the apparatus comprises a first radiation source arranged on a first side of the vehicle path that emits a radiation beam towards a second, opposite side of the vehicle path; a first reflector arranged on the second side of the vehicle path from the first radiation source that receives the beam from the first radiation source and reflects the beam in a direction generally parallel to the vehicle path; a second reflector arranged on the second side of the vehicle path that receives the reflected radiation from the first reflector, and reflects its towards the first side of the vehicle path; and a first radiation detector arranged at the first side of the vehicle path that receives the reflected radiation from the second reflector.
In another aspect the invention provides in an embodiment an apparatus for measuring at least one of a speed and acceleration of a vehicle travelling on a vehicle path, the apparatus that comprises a first radiation source arranged at a first side of the vehicle path that emits radiation; a beam splitter arranged at the first side of the vehicle path that receives the radiation from the first radiation source and splits the received beam into two partial beams, with one partial beam directed across the vehicle path towards a second side of the vehicle path opposite the first side of the vehicle path, and a second partial beam; and a first reflector mounted on the first side of the vehicle path that directs the second partial beam towards the second side of the vehicle path; a first detector on the second side of the vehicle path that receives the first partial beam from the beam splitter; and a second detector on the second side of the vehicle path that receives the second beam from the first reflector.
In another aspect, the invention provides in an embodiment a method for measuring at least one of the speed and/or acceleration of the vehicle, the method comprising the steps of: projecting a beam from a first side of the vehicle path towards a second, opposite side of the vehicle path; reflecting the beam, at the second side of the vehicle path, generally in a direction along the vehicle path; reflecting the beam from the second side of the vehicle path towards the first side of the vehicle path, and detecting the reflected beam at the first side of the vehicle path.
In another aspect, the invention provides a method for measuring at least one of the speed and/or acceleration of the vehicle, the method comprising the steps of: projecting a radiation beam at a first side of the vehicle path; splitting the radiation beam into two partial radiation beams; reflecting one of the two partial radiation beams across the vehicle path; reflecting the other of the two partial radiation beams across the vehicle path; detecting the first reflected partial radiation beam; and detecting the second partial reflected radiation beam.
In another aspect, the invention provides an apparatus and method that detects the mass of a passing vehicle.
There has thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract included below, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.